cMPL-Based Purification and Depletion of Human Hematopoietic Stem Cells: Implications for Pre-Transplant Conditioning

The transplantation of gene-modified autologous hematopoietic stem and progenitor cells (HSPCs) offers a promising therapeutic approach for hematological and immunological disorders. However, this strategy is often limited by the toxicities associated with traditional conditioning regimens. Antibody-based conditioning strategies targeting cKIT and CD45 antigens have shown potential in mitigating these toxicities, but their long-term safety and efficacy in clinical settings require further validation. In this study, we investigate the thrombopoietin (TPO) receptor, cMPL, as a novel target for conditioning protocols. We demonstrate that high surface expression of cMPL is a hallmark feature of long-term repopulating hematopoietic stem cells (LT-HSCs) within the adult human CD34+ HSPC subset. Targeting the cMPL receptor facilitates the separation of human LT-HSCs from mature progenitors, a delineation not achievable with cKIT. Leveraging this finding, we developed a cMPL-targeting immunotoxin, demonstrating its ability to selectively deplete host cMPLhigh LT-HSCs with a favorable safety profile and rapid clearance within 24 hours post-infusion in rhesus macaques. These findings present significant potential to advance our understanding of human hematopoiesis and enhance the therapeutic outcomes of ex vivo autologous HSPC gene therapies.

Activity of Plasmodium vivax promoter elements in Plasmodium knowlesi, and a centromere-containing plasmid that expresses NanoLuc throughout the parasite life cycle

Background

Plasmodium knowlesi is now the major cause of human malaria in Malaysia, complicating malaria control efforts that must attend to the elimination of multiple Plasmodium species. Recent advances in the cultivation of P. knowlesi erythrocytic-stage parasites in vitro, transformation with exogenous DNA, and infection of mosquitoes with gametocytes from culture have opened up studies of this pathogen without the need for resource-intensive and costly non-human primate (NHP) models. For further understanding and development of methods for parasite transformation in malaria research, this study examined the activity of various trans-species transcriptional control sequences and the influence of Plasmodium vivax centromeric (pvcen) repeats in plasmid-transfected P. knowlesi parasites.

Methods

In vitro cultivated P. knowlesi parasites were transfected with plasmid constructs that incorporated Plasmodium vivax or Plasmodium falciparum 5′ UTRs driving the expression of bioluminescence markers (firefly luciferase or Nanoluc). Promoter activities were assessed by bioluminescence, and parasites transformed with human resistant allele dihydrofolate reductase-expressing plasmids were selected using antifolates. The stability of transformants carrying pvcen-stabilized episomes was assessed by bioluminescence over a complete parasite life cycle through a rhesus macaque monkey, mosquitoes, and a second rhesus monkey.

Results

Luciferase expression assessments show that certain P. vivax promoter regions, not functional in the more evolutionarily-distant P. falciparum, can drive transgene expression in P. knowlesi. Further, pvcen repeats may improve the stability of episomal plasmids in P. knowlesi and support detection of NanoLuc-expressing elements over the full parasite life cycle from rhesus macaque monkeys to Anopheles dirus mosquitoes and back again to monkeys. In assays of drug responses to chloroquine, G418 and WR9910, anti-malarial half-inhibitory concentration (IC₅₀) values of blood stages measured by NanoLuc activity proved comparable to IC₅₀ values measured by the standard SYBR Green method.

Conclusion

All three P. vivax promoters tested in this study functioned in P. knowlesi, whereas two of the three were inactive in P. falciparum. NanoLuc-expressing, centromere-stabilized plasmids may support high-throughput screenings of P. knowlesi for new anti-malarial agents, including compounds that can block the development of mosquito- and/or liver-stage parasites.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03773-4.

BCL11A enhancer-edited hematopoietic stem cells persist in rhesus monkeys without toxicity

Gene editing of the erythroid-specific BCL11A enhancer in hematopoietic stem and progenitor cells (HSPCs) from patients with sickle cell disease (SCD) induces fetal hemoglobin (HbF) without detectable toxicity, as assessed by mouse xenotransplant. Here, we evaluated autologous engraftment and HbF induction potential of erythroid-specific BCL11A enhancer-edited HSPCs in 4 nonhuman primates. We used a single guide RNA (sgRNA) with identical human and rhesus target sequences to disrupt a GATA1 binding site at the BCL11A +58 erythroid enhancer. Cas9 protein and sgRNA ribonucleoprotein complex (RNP) was electroporated into rhesus HSPCs, followed by autologous infusion after myeloablation. We found that gene edits persisted in peripheral blood (PB) and bone marrow (BM) for up to 101 weeks similarly for BCL11A enhancer- or control locus-targeted (AAVS1-targeted) cells. Biallelic BCL11A enhancer editing resulted in robust γ-globin induction, with the highest levels observed during stress erythropoiesis. Indels were evenly distributed across PB and BM lineages. Off-target edits were not observed. Nonhomologous end-joining repair alleles were enriched in engrafting HSCs. In summary, we found that edited HSCs can persist for at least 101 weeks after transplant and biallelic-edited HSCs provide substantial HbF levels in PB red blood cells, together supporting further clinical translation of this approach.

Plasmodium vivax chloroquine resistance links to pvcrt transcription in a genetic cross

Mainstay treatment for Plasmodium vivax malaria has long relied on chloroquine (CQ) against blood-stage parasites plus primaquine against dormant liver-stage forms (hypnozoites), however drug resistance confronts this regimen and threatens malaria control programs. Understanding the basis of P. vivax chloroquine resistance (CQR) will inform drug discovery and malaria control. Here we investigate the genetics of P. vivax CQR by a cross of parasites differing in drug response. Gametocytogenesis, mosquito infection, and progeny production are performed with mixed parasite populations in nonhuman primates, as methods for P. vivax cloning and in vitro cultivation remain unavailable. Linkage mapping of progeny surviving >15 mg/kg CQ identifies a 76 kb region in chromosome 1 including pvcrt, an ortholog of the Plasmodium falciparum CQR transporter gene. Transcriptional analysis supports upregulated pvcrt expression as a mechanism of CQR.

[A new technique to facilitate donor preparation for DMEK surgery]

BACKGROUND

Descemet membrane endothelial keratoplasty (DMEK) is becoming more and more the method of choice to treat corneal endothelial diseases in specialized centers. The reasons that prevent this technique from becoming widespread are the delicate donor tissue preparation. By inverting the curvature of the cornea from convex to concave after mounting onto an artificial anterior chamber, we developed a combined manual delamination and hydrodissection technique, which allows a rapid and endothelium-preserving method of separating donor Descemet membranes from the underlying stroma.

MATERIAL AND METHODS

Experiments were perfomed with 60 donor corneas that were not suitable for transplantation. Donor age ranged between 42 and 94 years. Two experimental groups were formed: 1 inverse manual delamination (n = 16) and 2 combined manual delamination and hydrodissection (n = 44). All experiments were undertaken by an experienced surgeon who was, however, not experienced with these techniques. We examined the frequency of Descemet membrane rupture as well as the amount of induced endothelial damage (trypan blue staining with quantitative image analysis).

RESULTS

Significant lesions of Descemet's membrane that would have led to a loss of the graft occurred in 25% of the manual delamination cases and in 4.5% using the combined technique. Endothelial damage induced by both techniques was low (6 and 5.2%, respectively).

CONCLUSION

For DMEK donor preparation, a combination of manual delamination and hydrodissection was shown to be a safe and endothelium-protective technique to separate Descemet membranes from the underlying stroma. A very rapid learning curve for the combination technique is of specific additional interest for beginners in DMEK surgery.

Bumblebee Flight in Heavy Turbulence

High-resolution numerical simulations of a tethered model bumblebee in forward flight are performed superimposing homogeneous isotropic turbulent fluctuations to the uniform inflow. Despite tremendous variation in turbulence intensity, between 17% and 99% with respect to the mean flow, we do not find significant changes in cycle-averaged aerodynamic forces, moments, or flight power when averaged over realizations, compared to laminar inflow conditions. The variance of aerodynamic measures, however, significantly increases with increasing turbulence intensity, which may explain flight instabilities observed in freely flying bees.

The importance of repeated measurements of the sFlt-1/PlGF ratio for the prediction of preeclampsia and intrauterine growth restriction

AIMS

The sFlt-1/PlGF ratio has been evaluated as a diagnostic marker for preeclampsia (PE). The aim of this study was to explore the use of the sFlt-1/PlGF ratio as an aid in prediction for PE.

METHODS

150 patients with a high risk for PE were enrolled in this prospective study. Groups were compared according to the pregnancy outcome: controls (n=114), intrauterine growth restriction (IUGR) (n=14) and PE (n=22) with subclassification early PE<34 weeks (n=6). Measurements of sFlt-1 and PlGF were performed on the automated Elecsys system. Statistical comparison of the sFlt-1/PlGF ratio in different outcome groups and a mixed model analysis using random intercept models were performed.

RESULTS

The sFlt-1/PlGF ratio was significantly higher in pregnancies complicated by PE up to 4 weeks before clinical diagnosis compared to controls (106.7 ± 47.7 vs. 21.0 ± 4.1; P=0.02). Levels of the sFlt-1/PlGF ratio were higher throughout pregnancy in women with IUGR compared to PE/control patients (intercept 1.57 vs. 1.30/0.67; P<0.05). The slope for the sFlt-1/PlGF ratio was significantly higher in PE and IUGR pregnancies compared to controls, indicating that a steep increase of the sFlt-1/PlGF ratio correlates with pathologic pregnancy outcomes.

CONCLUSION

The sFlt-1/PlGF ratio can identify pathologic pregnancy outcomes such as IUGR and PE before clinical diagnosis. Repeated measurements are necessary to assess the dynamics in serum values. The time-dependent slope of the sFlt-1/PlGF ratio is predictive for future pregnancy outcome and risk of developing preeclampsia.

Automated measurement of sFlt1, PlGF and sFlt1/PlGF ratio in differential diagnosis of hypertensive pregnancy disorders

OBJECTIVES

The utility of angiogenic and antiangiogenic biomarkers as diagnostic tools in preeclampsia (PE) has been shown in previous studies. Our study's aim was to evaluate the use of automated measurement of sFlt1, PlGF and their ratio (sFlt1/PlGF) in differential diagnosis of hypertensive pregnancy disorders.

PATIENTS/METHODS

Sixty-four patients with PE/HELLP, 18 with pregnancy-induced hypertension (PIH), 22 with gestational proteinuria (GP) and 232 controls were investigated. The PE/HELLP group was divided into mild PE (mPE, n=31), severe PE (sevPE, n=20), superimposed PE (supPE, n=7) and HELLP syndrome (n=6). sFlt1 and PlGF were measured in serum samples on an automated platform. Statistical analysis was performed using parametric and non-parametric methods, ROC analysis and logistic regression method.

RESULTS

PE patients showed higher sFlt1 and ratio and lower PlGF than controls (median ± SEM in pg/mL; 10888 ± 878 versus 2456 ± 116; 268 ± 39 versus 16 ± 2 and 68 ± 6 versus 439 ± 37, each p<0.001), subgroups showed similar differences in ratios (median ± SEM; supPE: 202 ± 110; mPE: 137 ± 27; sevPE: 497 ± 91; HELLP syndrome: 254 ± 72 versus controls 16 ± 2, each p<0.001). ROC analysis showed best performance for sFlt1/PlGF (AUC all PE: ratio 96.4%, sFlt1 92.8%, PlGF 92.4%, supPE: ratio 93.6%, mPE: ratio 94.8%, sevPE: ratio 99.4%, HELLP: ratio 98.6%, each versus controls). Patients with PIH and GP showed significant differences compared to controls (p ≤ 0.01, respectively), mPE (p ≤ 0.007), sevPE (p<0.001) and HELLP syndrome (p ≤ 0.003).

CONCLUSION

The automated measurement of sFlt1/PlGF is a reliable diagnostic tool in differential diagnosis of hypertensive pregnancy disorders and gives additional valuable information for clinical management.

The sFlt-1/PlGF ratio in different types of hypertensive pregnancy disorders and its prognostic potential in preeclamptic patients

OBJECTIVE

The soluble fms-like tyrosine kinase (sFlt-1)/placental growth factor (PlGF) ratio is a reliable tool in the assessment of preeclampsia. We tested the hypothesis that the sFlt-1/PlGF ratio is able to identify women at risk for imminent delivery. We characterized the sFlt-1/PlGF ratio in different types of hypertensive pregnancy disorders.

STUDY DESIGN

We investigated 388 singleton pregnancies with normal pregnancy outcome, 164 with PE, 36 with gestational hypertension, and 42 with chronic hypertension. sFlt-1 and PlGF were measured in serum samples.

RESULTS

Patients with preeclampsia had a significantly increased sFlt-1/PlGF ratio as compared with controls and with patients with chronic and gestational hypertension in <34 weeks and ≥34 weeks (P < .001). Time to delivery was significantly reduced in women with preeclampsia in the highest quartile of the sFlt-1/PlGF ratio (P < .001).

CONCLUSION

The sFlt-1/PlGF ratio allows the identification of women at risk for imminent delivery and is a reliable tool to discriminate between different types of pregnancy-related hypertensive disorders.

Contrast-enhanced adenosine-stress magnetic resonance imaging--feasibility and practicability of a protocol for detection or exclusion of ischemic heart disease in an outpatient setting

BACKGROUND

Evaluating myocardial function, assessing ischemic myocardial areas and detecting myocardial viability are necessary diagnostic information for guiding further therapy in patients with angina. The aim of this study was to show feasibility and safety of a compiled contrast- enhanced magnetic resonance imaging (ceMRI) protocol providing the above mentioned diagnostic possibilities and to demonstrate its applicability in daily routine.

METHODS

Consecutive patients with angina were screened on a 1.5 Tesla system. Functional images in short and long axis orientation were acquired for each patient. First-pass kinetics of a gadolinium-based contrast agent (0.1 mmol/kg) were measured after three minutes of stress with adenosine infusion (140 microg/kg/min). 10 min after a second bolus injection of contrast agent "late enhancement" (MLE) sequences were acquired for the detection of myocardial necrosis.

RESULTS

We enrolled 3174 patients referred for ceMRI for detection or exclusion of ischemic heart disease. One patient experienced a major complication due to hyperventilation followed by grand mal seizure. In 1121 (35.3%) patients minor complications, such as mild chest pain or dyspnea (30%), temporarily and asymptomatic AV block (3%) or nausea (2%) could be observed under adenosine infusion. Hypoperfusion in more than one myocardial segment and affecting more than 1/3 of the myocardial wall diameter could be detected in 1972 (62%) patients. Subendocardial hypoperfusion with limited duration could be shown in 897 (28%) patients. In 305 (10%) patients hypoperfusion could be excluded. MLE could be seen in 532 (17%) patients.

CONCLUSION

This compiled ceMRI protocol is suitable for detection or exclusion of ischemic heart disease in an outpatient routine. We showed feasibility, applicability and safety of our protocol. CeMRI may serve as a useful surrogate for non-invasive diagnostics prior to invasive coronary angiography in many outpatients.

Molecular dynamics simulations of stratum corneum lipid models: fatty acids and cholesterol

We report the results of an investigation on stratum corneum lipids, which present the main barrier of the skin. Molecular dynamics simulations, thermal analysis and FTIR measurements were applied. The primary objective of this work was to study the effect of cholesterol on skin structure and dynamics. Two molecular models were constructed, a free fatty acid bilayer (stearic acid, palmitic acid) and a fatty acid/cholesterol mixture at a 1:1 molar ratio. Our simulations were performed at constant pressure and temperature on a nanosecond time scale. The resulting model structures were characterized by calculating surface areas per headgroup, conformational properties, atom densities and order parameters of the fatty acids. Analysis of the simulations indicates that the free fatty acid fraction of stratum corneum lipids stays in a highly ordered crystalline state at skin temperatures. The phase behavior is strongly influenced when cholesterol is added. Cholesterol smoothes the rigid phases of the fatty acids: the order of the hydrocarbon tails (mainly of the last eight bonds) is reduced, the area per molecule becomes larger, the fraction of trans dihedrals is lower and the hydrophobic thickness is reduced. The simulation results are in good agreement with our experimental data from FTIR analysis and NIR-FT Raman spectroscopy.

[Cavernous hemangioma of the maxillary sinus]

Cavernous haemangioma of the paranasal sinuses is very rare. We describe the X-ray and CT findings in a case of cavernous haemangioma which originated from the mucous membrane of the maxillary sinus and eroded the bony boundary of the sinus.

The influence of angiotensin II antagonist postischemic acute renal failure

In 34 dogs the effect of a 90-min period of warm ischemia on renal perfusion and function was studied with and without (Sar1, Ile8) angiotensin II treatment. In the first 3 h after the release of renal arterial occlusion, a significant influence of the angiotensin II antagonist on changes in postischemic vascular resistance, intrarenal hemodynamics and renal function could be demonstrated, all being well preserved in the treated group.

[Avulsio bulbi (author's transl)]

It is reported about a 14 year old girl, sustaining an avulsion of the left eye-ball by a coat-rack. The optic nerve was cutted 18 mm retrobulbarly. In perimetry of the fellow-eye a temporo-superior defect was found as proof of traumatisation of the anterior-loop-fibers in the chiasm.

[The influence of dopamine of kidney function during continuous positive-pressure ventilation (PEEP) (author's transl)]

In a group of 20 patients the influence of continuous positive-pressure Ventilation (PEEP) on cardiac output, kidney function and renal and intrarenal hemodynamics was investigated. During ventilation with PEEP 10 ccm H2O a reduction of cardiac output, glomerular filtrationrate, sodium excretion and urinary output was observed. Renal blood flow, especially the cortical fraction, also decreased. Dopamine infusion, in a dose of 4 ng.kg-1.min-1, during continuous PEEP-ventilation, induced an increase of cardiac output, glomerular filtrationrate, renal sodium excretion and diuresis. The decreased renal cortical perfusion particularly was improved by Dopamine application.

[Aqueous-and serum levels of cephalexin and penicillin V after oral application in man (author's transl)]

This clinical study implies orally administered cephalexin and penicillin V as agents with effective aqueous homor penetration in noninfected human eyes. Aqueous humor concentration of cephalexin increases up to 15% of the serum level 2 h after application. Administration of 1 g or 2 g cephalexin revealed no significant difference in aqueous humor concentration. So penetration of blood-aqueous-humor barrier can be regarded as a saturation process. Individual results of 92 cephalexin determinations are variant and not related to body weight or age of the patients.

[Treatment of retinal detachment with macular hole: scleral buckling with an absorbable fibrin sponge (author's transl)]

In 21 patients with macular hole and retinal detachment a macular buckling procedure was performed including diathermic or cryogenic coagulation. An absorbable fibrin sponge (Fibrospum) was used as a new buckling material, which needs not to be sutured to the sclera at the posterior pole. In comparison to other procedures the use of fibrin sponge seems to be more simple and at least of the same results.

[Prophylactic lasercoagulation of senile retinoschisis (author's transl)]

135 patients with senile retinoschisis were treated by argon laser coagulation. 73 of them were reexamined after an average interval of 15 months. The treatment consisted of a posterior demarcation by 2-3 lasercoagulation series in the area of the normal retina and in addition treatment of the entire area of retinoschisis. Lasercoagulation was performed, when: 1. the retinoschisis reached the equator or extended postequatorially, 2. a hole in the outer layer was detected, 3. a retinal detachment proceeded from a retinoschisis in the other eye.